Integrated gold-disk microelectrode modified with iron(II)-phthalocyanine for nitric oxide detection in macrophages

Catalytic selectivity of metallophthalocyanines for electrochemical nitric oxide sensing

The catalytic properties of metallophthalocyanine (MPc) complexes have long been applied to electrochemical sensing of nitric oxide (NO) to amplify sensitivity and reduce the substantial overpotential required for NO oxidation. The latter point has significant ramifications for in situ amperometric detection, as large working potentials oxidize biological interferents (e.g., nitrite, L-ascorbate, and carbon monoxide). Herein, we sought to isolate and quantify, for the first time, the selectivity benefits of MPc modification of glassy carbon electrodes. A series of the most catalytically active MPc complexes towards NO, including Fe(II)Pc, Co(II)Pc, Ni(II)Pc, and Zn(II)Pc, was selected and probed for NO sensing ability under both differential pulse voltammetry (DPV) and constant potential amperometry (CPA). Data from DPV measurements provided information with respect to MPc signal sensitivity amplification (~1.5×) and peak shifting (100-200 mV). Iron-Pc exerted the most specific catalytic activity towards NO over nitrite. Catalyst-enabled reduction of the working potential under CPA was found to improve selectivity for NO over high potential interferents, regardless of MPc. However, impaired selectivity against low potential interferents was also noted.

Au nanoparticles-3D graphene hydrogel nanocomposite to boost synergistically in situ detection sensitivity toward cell-released nitric oxide

In situ detection of nitric oxide (NO) released from living cells has become very important in studies of some critical physiological and pathological processes, but it is still very challenging due to the low concentration and fast decay of NO. A nanocomposite of Au nanoparticles deposited on three-dimensional graphene hydrogel (Au NPs-3DGH) was prepared through a facile one-step approach by in situ reduction of Au(3+) on 3DGH to build a unique sensing film for a strong synergistic effect, in which the highly porous 3DGH offers a large surface area while Au NPs uniformly deposited on 3DGH efficiently catalyze the electrochemical oxidation of NO for sensitive detection of NO with excellent selectivity, fast response, and low detection limit. The sensor was further used to in situ detect NO released from living cells under drug stimulation, showing significant difference between normal and tumor cells under drug stimulation.

Nitric oxide selective electrodes

Since nitric oxide (NO) was identified as the endothelial-derived relaxing factor in the late 1980s, many approaches have attempted to provide an adequate means for measuring physiological levels of NO. Although several techniques have been successful in achieving this aim, the electrochemical method has proved the only technique that can reliably measure physiological levels of NO in vitro, in vivo, and in real time. We describe here the development of electrochemical sensors for NO, including the fabrication of sensors, the detection principle, calibration, detection limits, selectivity, and response time. Furthermore, we look at the many experimental applications where NO selective electrodes have been successfully used.